Single handle mixing valves are well known and common in the plumbing field. These valves provide a stream of mixed water from separate hot and cold water streams. However, these valves are subject to the inconvenience that may result from a sudden undesirable change in water temperature or pressure of the water in either of the lines supplying water to the valve. In some cases, the resulting change in the temperature of the mixed outlet water can result in discomfort to the user of the valve. The discomfort can be particularly pronounced when the valve is a shower mixing valve and the user is within the shower stall. A sudden pressure drop in the cold water line, such as that which frequently occurs when a toilet is flushed, will cause a sudden increase in the temperature of the shower water, requiring the user to move quickly away from the stream of water.
Several faucets and mixing valves have been developed in an attempt to reduce or eliminate this problem. U.S. Pat. No. 4,699,172 provides a self-regulating valve assembly for combining pressurized hot and cold water to produce an output of mixed water having a preselected constant water temperature. The valve assembly comprises a housing having a valving cavity, a hot water inlet leading to the valving cavity, a cold water inlet leading to the valving cavity, and a mixed water outlet passageway leading from the valving cavity. A valve member translates in the valving cavity and divides the cavity into two auxiliary chambers. A passageway through the valve member allows fluid to flow from each of the inlets to the outlet passageway at a rate that varies as the valve member translates. Passageways in the valve member permit a portion of the mixed water to flow into the auxiliary chambers. An auxiliary passageway is provided between each of the auxiliary chambers and the outlet passageway. A temperature responsive element is provided within the outlet passageway. In response to a deviation in the temperature of water in the mixing chamber the temperature responsive element closes one of the auxiliary passageways causing the valve member to translate until the water in the outlet passageway reaches the preselected temperature.
U.S. Pat. No. 4,901,750 discloses a pressure balanced, volume controlled and temperature controlled mixing valve. This mixing valve has a modular cartridge rotatably mounted in the housing. The cartridge has a bottom volume control valve plate attached to a lower section housing a pressure balance valve. The lower section is secured to an upper section that rotatably receives temperature control plates. The plates are both rotatable about a common axis. One plate is controlled by operation of a first stem attached to a handle. The other plate is controlled by a second stem which is operated by a temperature control knob. An insert allows the temperature control knob to operate even when hot and cold water supplies are inverted. A splined hot water stop ring sits in the handle and adaptably limits rotation of the temperature control knob for a selected maximum water temperature. Outer seals assure that all water flows through the cartridge when the volume is set for partial flow.
U.S. Pat. No. 3,713,301 discloses a valve construction having a hot water inlet connected with the mixing chamber, a cold water inlet connected with the mixing chamber, and a water discharge outlet from said mixing chamber. One or more valve seats are provided in one or more of the inlets. One or more diaphragms are provided in modulating relationship with one or more of said valve seats. Each diaphragm construction includes a pilot passageway and bleed opening and an adjustable pilot in modulating relationship with the valve seat. A thermostat construction is responsive to the mixed water temperature of the mixing chamber and has adjusting means to adjust one or more pilots in modulating relationship to the water passageways in the one or more diaphragms. The thermostat construction may adjust the hot and/or cold water pilot to introduce a proper amount of hot and/or cold water into the mixing chamber. The pilot or pilots may be encased in a cavity wall construction which provides a cavity on one side of the diaphragm. One or more levers are provided with inner ends in the cavities and with sealing outward connections, so that their outer ends may be actuated by the thermostat construction to provide the modulating water control for the hot and/or cold water.
U.S. Pat. No. 3,550,901 discloses a valve construction having a hot water inlet connected with a mixing chamber, a cold water inlet connected with the mixing chamber, and a water discharge outlet from said mixing chamber. One or more valve seats are provided in one or more of the inlets. One or more diaphragms are provided in modulating relationship with one or more of said valve seats. Each diaphragm construction includes a pilot passageway and bleed opening and an adjustable pilot in modulating relationship with the valve seat. A thermostat construction is responsive to the mixed water temperature of the mixing chamber and has adjusting means to adjust one or more pilots in modulating relationship to the water passageways in the one or more diaphragms. The thermostat construction may adjust the hot and/or cold water pilot to introduce a proper amount of hot and/or cold water into the mixing chamber. The pilot or pilots may be encased in a cavity wall construction which provides a cavity on one side of the diaphragm. One or more levers are provided with inner ends in the cavities and with sealing outward connections, so that their outer ends may be actuated by the thermostat construction to provide the modulating water control for the hot and/or cold water.
U.S. Pat. No. 3,388,861 discloses a mixing valve comprising a valve body with hot and cold water inlet ports and an outlet port, an inner member sliding in the valve body and having hot and cold water inlet port means and outlet port means and an adjustment member slidable within the control valve under the actuation of a thermostat element to control the amount of water passing respectively through the hot and cold water inlet port means.
U.S. Pat. No. 3,004,710 discloses an adjustable thermostatic mixing valve having a valve body with hot and cold water inlets leading thereinto, with an outlet leading therefrom. The outlet is provided with an electrically controlled shut-off valve.
One feature of the present invention is that it provides a reliable compact thermostatically controlled valve wherein all the valving elements and temperature sensing elements are provided within a replaceable, easily removable cartridge assembly. An advantage of this configuration is that the cartridge may be retrofitted to existing single handle faucet sockets.
Another feature of the present invention is that the thermostatic valve is not affected directly by changes in pressure in either of the water supply lines, but instead is affected only by the temperature of the mixed water. The advantage to this design is that the valve will produce a more nearly isothermal output than previous valves.